Stylus pen



FIG. 1 is a perspective view of our new design for a stylus pen;

FIG. 2 is a front elevational view thereof, the side rotated 120 degrees, and the side rotated 240 degrees are identical;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a bottom plan view thereof. 

The ornamental design for a stylus pen, as shown and described. 